1. Field of the Invention
This invention concerns a ball spline bearing assembly and, in particular, it relates to a ball spline bearing assembly of a type in which an outer ring of the bearing assembly engages therein a track shaft axially and movably by way of rolling contact of balls contained along the endless raceways formed axially to the inner surface of the outer ring.
2. Description of the Prior Art
Ball spline bearing assemblies and ball slide mechanisms employing them have been proposed and put to practice in recent years, for example, as disclosed in U.S. Pat. Nos. 3,897,982, 4,040,679, or the like. Known ball spline bearing assemblies generally comprise, in combination, an outer ring capable of engaging therein a track shaft axially and slidably and formed with a plurality of axial ball circuits each consisting of a non-load raceway and a load raceway in pair, balls circulated in an endless manner in the ball circuits and a ball cage coaxially combined to the inner side of the outer ring so as to retain the balls while partially exposing them through the slots for rolling contact with the slide surface of the track shaft.
These known assemblies, however, are not quite satisfactory in that they are difficult to fabricate since the structure of the ball cage is much complicated because the cage has to be aligned directly to the outer ring upon setting up of the assembly. This also presents a difficulty in attaining a desired accuracy for the fabrication of the ball slots in the ball cage. In addition, while, in one of such known ball spline bearings, lubrication has been effected, for example, by feeding lubricant only to one of a plurality of ball raceways to wet the balls therein, which then transfer the attached lubricant during rolling movement by way of the track shaft to the balls in other ball raceways, it takes too much time for complete lubrication throughout the entire raceways often resulting in lubrication with metal dust-contaminated lubricant to thereby impair the performance and decrease the service life of the ball bearings.